Page 252 - Materials Chemistry, Second Edition

242 G. A. da Silva et al.

1 Introduction

With the growing interest on environmental issues, fostered by academic, gov-
ernmental, and private initiatives, life-cycle assessment (LCA) has become an
increasingly prominent tool in evaluating the environmental performance of
products and services, presenting benefits in comparison with more conservatives
and less holistic approaches.
Notwithstanding their diverse benefits, LCA’s ability to support and influence
decision-making processes in which the environmental dimension is taken into
account is conditioned to some structural factors of the methodology, such as data
quality and representativeness. Moreover, the interest of potential LCA users
depends on the relationship of cost and duration of the study versus its precision
and depth. Those aspects led LCA practitioners to make some investments on
databases development, which are constructed, generally, by life-cycle inventories
(LCI), which can be understood as a set of information regarding material and
energetic flows consumed from the environment, or disposed in it, from an
anthropic activity. Among the most requested LCIs are those dealing with energy
sources. Every material or product needs energy in different stages of their life
cycles. This energy can be obtained from various sources in different locations.
Since the beginning of LCA studies, during the 1970s, energetic LCIs have
been developed for systems located in developed countries, in which the electricity
generation is usually focused on thermal sources (by fossil fuels like coal, gas, and
oil) and nuclear. On this context, very few countries use hydropower as a sig-
nificant source of electricity, and consequently, LCIs for hydropower are quite
scarce. Complementarily, the greatest parts of the existent studies focus on very
few aspects—generally greenhouse gas (GHG) emissions from the reservoir
flooding.
In terms of LCA, hydropower is not a traditional subject, because most of the
total environmental load relies on civil construction, and not on a transformation
process that could be described in terms of an input/output balance. Besides due to
the intrinsic characteristics of hydropower generation, one study can hardly be
representative of any other enterprise or plant in the same segment. Hydropower
uses the local land relief to create the dam and associated reservoir. Each project
has its own conception and methods, significantly altering the environmental
burdens associated with the construction procedures and materials choices, deeply
changing both the construction machines used and the materials consumption,
modifying their associated life cycle.
This chapter aims to give a contribution for LCA practitioners presenting and
discussing methodological considerations about LCI for hydropower in order to
better understand the subject. It starts with a brief review of the most prominent
studies on the area and some general considerations regarding each specific def-
inition within the ‘‘scope definition’’ step of the LCA methodology, focusing on
materials and energy flows (and not only on greenhouse gas emissions). Special
attention is given for the requirements for product system modeling. In order to